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\begin{equation*}\frac{2}{3} \cdot \frac{9}{4} - \frac{3}{4} = \frac{18}{12} - \frac{3}{4} = \frac{3}{2} - \frac{3}{4} = \frac{6}{4} - \frac{3}{4} = \frac{3}{4}\end{equation*}
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